97 Outback Legacy.Check Engine Codes P0301,P0303.Misfires in Cylinders 1 and 3.Distributor Coil has been replaced.I swapped out distributor wire from cylinder2 to cylinder 1 still same errors.If I replace spark plugs and perform comprerssion test and the codes are still present what would the next step be?Or should I try something else first?

1&3 are on the same side. Usually a cam timing problem when 2 cylinders on the same bank are affected.

 

Has the timing belt ever been changed? Were the idlers and tensioner done at the same time?

The timing belt was changed recently along with water pump,belt tensioner and thermostat.Ran great for a couple of weeks.Then over this past weekend the check engine light came on and it started to run rough and have a low idle.After ten minutes the check engine light will flash.Both cams on the 1 and 3 side were replaced before I bought the car.

Edited January 27, 201610 yr by chris97subaru

Need to remove the belt cover and check the timing.

 

The camshafts were replaced? Any particular reason why? At idea if the valve clearances were set at that time?

Although probably not your particular issue, O2 sensors can cause random misfires. Depending on how bad they have shorted internally, they can cause other issues too, especially if they are screwing with the computer signal, and takes a few minutes to try and rule out.

 

 

If actual timing checks out to be OK, I'd disconnect the battery for a bit to reset the codes (you have been doing this between repairs, right?) then reconnect, start engine and see if codes even persist. If they do, disconnect neg terminal again and unhook both O2 sensors (don't let wiring loom sit on or near hot exhaust). Restart engine and see if the codes appearing are the same or not. Should get both O2 codes but hopefully no misfire codes as it should be running in a closed loop. 

 

Fairtax is probably right, but if not it won't hurt to rule them out. Should also inspect grounds and connections for corrosion, loose reconnects after previous repairs, brittle wires, improperly routed wiring that may have melted, etc.

Edited January 27, 201610 yr by Bushwick